well I would try a scalpel and cut under the foot of the shroom, you may be able to scrape them off that way, and it you so happen to cut part of the foot, it will grow back and the piece left on the rock will turn into a new mushroom.
an amazing thing with shrooms, you can cut them up like pizza, as long as you have a piece of the mouth connected to the cuttings they will reform into full shrroms in about 1-2 weeks, but shrooms tend to split pretty quickly aswell.
if you want fast reproduction once you get them off the rock cut afew like a pizza, grab a scalpel or sharp eyebrow scissors and cut them down the middle of the mouth.
let them sit in a seperate container with sand and little flow, in about 1 week they will be whole again and ready for mounting to plugs or rubble.
then even more shrooms to go around for dbtc
just my experience with all my shrooms in my tanks over the years, hope it helps.
robert - eastbayreefer2010